The present invention relates to an electronic photoflash system having features to avoid wasteful consumption of energy stored in a battery power supply when, for example, the user forgets or neglects to open a switch after the photoflash system has been fully charged or between successive uses of the system.
Electronic photoflash systems using battery power supplies and storage capacitors supplied with relatively high voltage, direct current from an oscillator-rectifier circuit to operate a flash lamp are well known in the art. In such systems the energy stored in the batteries can be rapidly consumed if the user is not careful to switch the batteries out of the circuit after the storage capacitor has been fully charged. If the energy of the batteries is thus consumed, the photoflash system may thereafter be unable to flash the flash lamp, and as a result it may not be possible to take important or valuable photographs. When commercially available batteries are used, it may be possible to replace the consumed batteries with new ones so that pictures can be taken, but often the fact that the batteries have run down is not recognized until the user attempts to take a photograph. Moreover, when nickel-cadmium type rechargeable batteries are used, it may not be possible to easily replace them and recharging may take too much time.
The present invention is intended to overcome or avoid these problems. The system according to the invention is simple in construction and has no expensive parts and, therefore, the photoflash system can be produced at a low cost. The invention includes a voltage source switching means which automatically opens the connection between the battery power supply and the photoflash circuitry should the user forget or neglect to open the switch manually. The voltage source switching means may, however, be manually closed for subsequent photoflash uses. Another advantage of the present invention is that when the voltage source switching means is opened, a readily noticeable sound is produced, mechanically, and the user is, therefore, able to know that the voltage source switch has automatically opened due to the period of time which has elapsed since the previous photoflash use. Still another advantage of the present invention is that the photoflash consumes a minimum of electric power and can be made small in size and light in weight because the switch closing operation is performed manually and the switch opening operation is controlled by a discharge current.